Inquiry Into Scientific Thinking The 10 Percent Rule Food chains show the path of energy through an ecosystem. As you move through the food chain, energy is lost. Scientists estimate only 10 percent of energy passes from one level to the next. This is why most food chains are not very long.
1. Look at the four empty 2-liter water bottles shown above. Remember 2 liters is the same as 2000 mL. 2. Imagine that the amount of water in a bottle represents energy in a food chain. The first bottle represents producers. Using a red pencil, color in the bottle so it is full. In other words, it has 2000 mL of water. This will represent 100% of the energy available. 3. Think about what the 10 percent rule says about energy. Look at the bottle representing first-level consumers. Use the red pencil to color in how much water (equivalent to energy) this bottle would contain. 4. Use the red pencil to color in the amount of water in the bottle for second-level consumers. 5. Use the red pencil to color in the amount of water in the bottle for third-level consumers. Analyze and Conclude 1. What do you notice about the water levels in the bottles as you move through the food chain?
2. How much water was available for the second-level consumer? A. 2000 mL C. 20 mL B. 200 mL D. 2 mL 3. Imagine this food chain: A hawk eats a robin. The robin ate a grasshopper. The grasshopper ate grass. Which organism is the source of energy for the food chain?
4. In a food chain, do the carnivores or the herbivores receive more of the energy supplied by the producers at the base of the food chain? Explain.
Inquiry Into Scientific Thinking
The 10 Percent Rule Food chains show the path of energy through an ecosystem. As you move through the food chain, energy is lost. Scientists estimate only 10 percent of energy passes from one level to the next. This is why most food chains are not very long.
1. Look at the four empty 2-liter water bottles shown above. Remember 2 liters is the same as 2000 mL.
2. Imagine that the amount of water in a bottle represents energy in a food chain. The first bottle represents producers. Using a red pencil, color in the bottle so it is full. In other words, it has 2000 mL of water. This will represent 100% of the energy available.
3. Think about what the 10 percent rule says about energy. Look at the bottle representing first-level consumers. Use the red pencil to color in how much water (equivalent to energy) this bottle would contain.
4. Use the red pencil to color in the amount of water in the bottle for second-level consumers.
5. Use the red pencil to color in the amount of water in the bottle for third-level consumers.
Analyze and Conclude
1. What do you notice about the water levels in the bottles as you move through the food chain?
2. How much water was available for the second-level consumer?
A. 2000 mL C. 20 mL
B. 200 mL D. 2 mL
3. Imagine this food chain: A hawk eats a robin. The robin ate a grasshopper. The grasshopper ate grass. Which organism is the source of energy for the food chain?
4. In a food chain, do the carnivores or the herbivores receive more of the energy supplied by the producers at the base of the food chain? Explain.